import java.util.HashSet;
import java.util.Set;

public class BUG1 {
    public static void main(String[] args) {
        Set<String> s = new HashSet<>();
        Set<Set<String>> ss = new HashSet<>();
        ss.add(new HashSet<>(s)); // 使用复制的方式添加 s 到 ss 中
        System.out.println(ss.contains(s));
        s.add("Hi");
        System.out.println(ss.contains(s));
        Set<Set<String>> ss2 = new HashSet<>(ss);
        System.out.println(ss2.contains(s));
        s.add("There");
        System.out.println(ss2.contains(s));
    }
}
